1. Field of the Invention
The present invention relates to a method and apparatus for speech recognition, and more particularly, to a user adaptive speech recognition method and apparatus that controls user confirmation of a recognition candidate using a new threshold value adapted to a user.
2. Description of Related Art
Speech recognition is a process that extracts features from an input speech, and after applying a pattern recognition algorithm, estimates whether a phoneme or word sequence is from a speaker.
In appliances that have a speech recognition function, such as a cellular phone, PDA, automobile navigation system, a user can input a control command through speech.
For example, when using an automobile navigation system that has a speech recognition function, a user can get destination information simply by speaking the destination address instead of pressing search buttons.
However, due to the features of speech there is a limitation to the recognition success rate. Accordingly, a conventional speech recognition technique first performs recognition for an input speech, and provides recognition candidates for the user to confirm the success of the recognition.
For example, if the speech recognition apparatus recognizes “Seoul Station” from the input speech, the speech recognition apparatus asks the user “Is Seoul Station Correct?” The user confirms the success or failure of the recognition by answering “Yes” or “No.”
If the answer is positive, the speech recognition apparatus decides the recognition has succeeded, and sends the corresponding recognition candidate as the result of recognition to an application unit.
However, the conventional technique causes a user inconvenience because every recognition result requires a confirmation process.
U.S. Pat. No. 6,567,778 entitled “Natural Language Speech Recognition Using Slot Semantic Confidence Scores Related to Their Word Recognition Confidence Scores” describes a technology that calculates confidence scores for an input speech and if the confidence score is over the threshold value, it outputs a corresponding recognition candidate as the result of recognition without a user confirmation process.
However, in U.S. Pat. No. 6,567,778, because every user has different speech features, and if a uniform threshold value is applied to every user, the frequency of user confirmations may not be reduced. Thus, the user still needs to perform a confirmation process for most recognition candidates.
Therefore, a technique is required that can increase the success rate of the speech recognition while decreasing the frequency of user confirmations.